Pumping unit for constant pulseless flow

ABSTRACT

A pumping unit for high pressure operation of the order of 10,000 psi or greater including upwards of 150,000 to 200,000 psi is disclosed which is essentially pulseless in its discharge, has no packing but utilizes plungers with hydrostatic supports and seals, and for this purpose two pumps and/or intensifiers are employed actuated by a cam directly or through fluid actuators for each cylinder. The cam has a constant rate of rise with a faster return rate. The return position is adjustable by a variably positioned stop or pick-off so that one cylinder will overcome compressibility and commence discharging fluid when the other cylinder finishes thereby providing a steady discharge flow rate. A simple low pressure hydraulic circuit and an air actuating circuit are described.

United States Patent 1191 1111 3,816,029 Bowen et al. 1 1' June 11, 1974 [5 PUMPING UNIT FOR CONSTANT 3,181,571 5/1965 Scheffel 417/521 x PULSELESS FLOW 3,354,792 11/1967 Fuchs 92/174 3,612,727 10/1971 Drake 417/388 [75] Inventors; John C. Bowen, Huntington Valley; 3,704,080 11/1972 Cross 417/486 Rush B. Gunther, Abington, both of Primary ExaminerCarlton R. Croyle [73] Assignee; The Durimn Company, Inc. Assistant Examiner-R chard E. Gluck Dayton Ohio Attorney, Agent, or Fzrm-Zachary T. Wobensmnh, 22 Filed: on. 3, 1972 2nd [21] Appl. No.: 294,637 [57] ABSTRACT A pumping unit for high pressure operation of the [52] US. Cl 4 /2 17/339, 4l /5 order of 10,000 psi or greater including upwards of 417/53 2/865, 4l7/569 150,000 to 200,000 psi is disclosed which is essentially f F041) 9/ F04b 17/00, F0 13 21/02 pulseless in its discharge, has no packing but utilizes 1 Field 01 Search plungers with hydrostatic supports and seals, and for 417/536, 319, 223, 539; 92/138, 3 this purpose two pumps and/or intensifiers are employed actuated by a cam directly or through fluid ac- [56] Re enc Clted tuators for each cylinder. The cam has a constant rate UNITED STATES PATENTS of rise with a faster return rate. The return position is 2,010,377 8/1935 Sassen 417/539 X adjustable a variakbly Positioned P f f' so 2,471,117 5/1949 Orshansky. 91/481 x that one Cylmder W111 Overcome compresslblllty and 2,546,034 3/1951 Lansing 417/223 X commence discharging fluid when the other cylinder 2,770,984 11/1956 Loecy 1 92/ 13.5 finishes thereby providing a steady discharge flow 2,771,845 11/1956 Eagan 417/458 X rate. A simple low pressure hydraulic circuit and an Soccal't air actuating circuit are described 2,980,024 4/1961 Pope 92/138 X 3,003,428 /1961 Christenson 417/536 13 Claims, 12 Drawing Figures 52 ya/ 4.9 2.9- )4740,4Z 34 33 33 47 4.9

1 1 I 1 26, 1 28 L 1 1 v11: I vcn V'c luuyj-zitu l: p VT 48 4a PATENTEDJUN 11 I974 Q SHEET 30? 5 PATENTEBJUII 1 1 I914 33% ska-2s saw u or s PUMPING UNIT FOR CONSTANT PULSELESS FLOW BACKGROUND OF THE INVENTION pumps to vary the stroke of the pump for volume or other control. Typical structures for this purpose are shown in U.S. Pats. to Denny, No. 2,612,839; Wolf, No. 212,777; Louis, No. 1,649,356; Eagen No. 2,771,845; Sato et al., No. 3,398,691; Dodson et al., No. 3,301,197; Sheen et al., No. 2,613,606; and Thurman, No. 2,863,471.

Saalfrank, in U.S. Pat. No. 2,620,734, undertakes to obtain constant volume fluid delivery but has very complex structure for this purpose.

It has also been proposed to use various packing ma terials in high pressure pumps but none of these has proven satisfactory for continuous operation say for 8,000 hours at nominal speeds of -30 cycles per minute and pressure levels above 10,000 psi.

In such pumps, if some leakage is permitted in order to reduce the friction between the packing and the plunger, erosion due to the fluid occurs with undesired increase in leakage. The action is accentuated if the leaking liquid is water because of its solvent action. Increase of pressure of water, also, does not bring about an increase in viscosity which is sufficient to decrease leakage.

If the packing is tight enough to prevent leakage then the friction between the packing and the plunger becomes so high that small particles of the packing material are torn off. Alternately, material is transferred to the plunger which then rips off larger portions of packing material. In addition to shortened packing life, particles of packing also cause check valve malfunction.

It has been recognized that hydrocarbon oils and certain other fluent materials become more viscous as the pressure is increased, (see Fuchs, U.S. Pat. No. 3,354,792), and this property is utilized in the apparatus of the present invention for centering the pump piston and prevention of process leakage with lubrication while maintaining steady or pulseless liquid delivery.

Other intensifiers have been proposed in U.S. Pats. to Douglas et al., No. 3,234,882 and Newhall No. 2,189,835, but these have various shortcomings as indicated above and are complex in construction.

SUMMARY OF THE INVENTION In accordance with the invention an intensifier pumping unit is provided in which a pulseless flow is obtained, a cam of special configuration being employed and structure associated with the cam gives an adjustable return stroke of the cam follower, the cam directly or through fluid systems with valves controlling the position of the pump pistons, the pistons preferably having a fluid seal utilizing a fluid whose viscosity increases substantially with increase of pressure.

It is the principal object of the invention of provide a pumping unit which has improved operating characteristics including smooth essentially pulseless delivery of a fluid at very high pressure and with freedom from interruption over extended periods of time of the order of 8,000 hours continuous duty at nominal speeds of 20-30 cycles per minute.

It is a further object of the invention to. provide a pumping unit which is relatively simple in construction and reliable in its action and eliminates the necessity for accumulators or for multi-stage and multiple cylinder pumps with complex valving with careful phasing.

It is a further object of the invention to provide an intensifier pumping unit which includes a variable volume pump having a continuous discharge and which can operate at slow speed as well as at high speeds.

It is a further object of the invention to provide a pumping unit of the character aforesaid with reduced tendency to heating and in which cooling is effected by the packing fluid.

Other objects and advantageous features of the invention will be apparent from the description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS The nature and characteristic features of the invention will be more readily understood from the following description taken in connection with the accompanying drawings forming part hereof, in which:

FIG. 1A is a diagrammatic view of a mechanical pumping unit in accordance with the invention;

FIG. 1B is a diagrammatic view of an intensifier pumping unit in accordance with the invention;

FIG. 1C is a diagrammatic view of another intensifier pumping unit in accordance with the invention;

FIG. 2 is a side elevational view of the high pressure cylinders, control valves therefor, cam and return stroke control mechanism in accordance with the invention shown in FIG. 1C;

FIG. 3 is an end elevational view of the structure of FIG. 2 as seen from the line 3-3 of FIG. 2;

FIG. is a horizontal sectional view taken approximately on the line 4-4 of FIG. 2;

FIG. 5 is a horizontal sectional viewtaken approximately on the line 5-5 of FIG. 2;

FIG. 6 is a vertical sectional view taken approximately on the line 6-6 of FIG. 5;

FIG. 7 is a vertical sectional view taken approximately on the line 7-7 of FIG. 5;

FIG. 8 is a diagrammatic view of another form of DESCRIPTION or THE PREFERRED EMBODIMENTS Referring now more particularly to FIGS. 1A and. 10 of the drawings, in which one form of pumping unit is shown diagrammatically, a cam 28 is provided.

The shape of the cam 28 and the stroke control structure is described in detail below. The cam 28 is secured to a shaft 29, driven by a cam operating motor 30, an

overload clutch 31 being interposed in the shaft 29. A speed controller 32 is provided for the motor 30 so that the motor 30 can be driven at the desired speed and thus determine the rate of feed of the high pressure fluid.

The cam 28 has followers 26 in engagement therewith carried by guides 33 in cylinders 42, the followers 26 being urged by springs 34 into cam engagement. The cylinders 42 have pump pistons 40 connected to the guides 33. Follower control plates 21 and 22 on threaded adjusting rods 23 are provided to control the return of the followers 26 to modify the cam action.

The pump cylinders 42 have valve heads 47 secured thereto with inlet and delivery check valves 48 and 49 connected thereto. The inlet check valves 48 have fluid connections 50 extending thereto from a source of liquid (not shown) to be pumped, such as a catalyst, to very high pressure with pulseless flow.

The delivery check valves 49 have a liquid delivery pipe 51 connected thereto for the delivery of the high pressure liquid. A pressure gage 52 may be connected to the pipe 51 for indicating the delivered pressure.

Referring now more particularly to FIG. 1B of the drawings in which another form of the invention is shown diagrammatically, a cam 28 is provided as before, secured to a shaft 29 and driven by a cam operating motor 30, an overload clutch 3.1 being interposed in the shaft 29. A speed controller 32 is provided for the motor 30 so that the motor 30 can be driven at the desired speed and thus determine the rate of feed of the high pressure fluid.

The cam 28 has followers 26 in engagement there-- with, carried by guides 74, which engage wedges 75 positioned as hereinafter explained, for controlling four way valves 76 connected to a supply of fluid under pressure and by pipes 77 and 7.8 to opposite sides of fluid operated pistons 79 in fluid cylinders 80. The pistons 79 are connected to pump pistons 40 in a pump cylinder 42. The pump cylinders 42 have inlet and delivery check valves 48 and 49 connected thereto. The inlet check valves 48 have fluid connections 50 extending thereto from a source of liquid (not shown) to be pumped, such as a catalyst, under very high pressure with pulseless flow. I

The delivery check valves 49 have a liquid delivery pipe 51 connected thereto for the delivery of the high pressure liquid. A pressure gage 52 can be connected to the pipe 51 for indicating the delivered pressure.

Follower control plates 21 and 22 on threaded adjusting rods 23 are provided to control the return of the followers 26 to modify the cam action.

The wedges 75 are connected by cords 82 extending overpulleys 83 and connected for movement with the pistons 79 and pistons 40 to provide a servo action with feedback.

Referring now more particularly to FIG. 1C of the drawings in which another form of the intensifier pumping unit is shown diagrammatically, a reservoir tank for liquid such as oil for the low pressure hydraulic circuit is shown with pumps 11 driven by a motor 12 having supply connections 13 extending into the liquid in the tank 10. The delivery connections of the pumps 11 are connected by pipes 14 to four way valves 15 of well known type, operated by valve operating structure such as operating rods 16. Thevalves 15 have return pipes 17 to the tank 10 and pressure relief valves 18 can be connected between the pipes 14 and 17 for excess pressure relief.

The pipes 14 and 17 can have non-retum or check valves 19 and 20 therein to prevent reversal of flow therethrough.

The valve operating rods 16 are preferably spring urged by springs 25 to urge their followers 26 into engagement with a cam 28. The shape of the cam 28 and the stroke control structure is described in detail below. The cam 28 is secured to a shaft 29, driven by a cam operating motor 30, an overload clutch 31 being interposed in the shaft 29. A speed controller 32 is provided for the motor 30 so that the motor 30 can be driven at the desired speed and thus determine the rate of feed of the high pressure fluid.

A servo action is desired and one suitable structure for the purpose utilizes the valves 15 which determine the delivery to and discharge of liquid from opposite ends of motor cylinders 35. The motor cylinders 35 preferably have flexible pipes 140 and 17a connected thereto and the cylinders 35 are preferably mounted for reciprocation and to provide a feed back. Each of the motor cylinders 35 has a motor piston 36 therein with a piston rod 37 extending therefrom through one with control valves 15 as referred to above are only required to generate sufficient pressure to keep the cylinders 35 in position.

The pumps 11 have capacity greater than that required to move the pistons 36, 136 at maximum design speed and excess fluid is diverted through the open centers of the spools of the valves 15 and or through valves 18 if high pressure discharge of the pump is blocked or if closed center spools are used in valves 15, 115.

Each of the motor cylinders 35 is shown as having a pump piston 40 extending from the end opposite the piston rod 37. The pump pistons 40 are each reciprocable in a pump cylinder 42 mounted in a housing 41 on the frame 38. The cylinders 42 have connections 43 which extend from a pump 44 for the supply of the lubricating seal fluid for the pistons 40. A fluid return connection 45 is provided for the return of the lubricating seal fluid.

The pump cylinders 42 have valve heads 47 secured thereto with inlet and delivery check valves 48 and 49 connected thereto. The inlet check valves 48 have fluid connections 50 extending thereto from a source of liquid (not shown) to be pumped such as a catalyst under very high pressure with pulseless flow.

The delivery check valves 49 have a liquid delivery pipe 51 connected thereto for the delivery of the high pressure liquid. A pressure gage 52 may be connected to the pipe 51 for indicating the delivered pressure.

Referring now more particularly to FIGS. 2 to 6 of the drawings, there is illustrated structural details of the principal parts of a preferred form of the unit shown diagrammatically in FIG. 1C.

The fixed frame F has the cam shaft 129 mounted thereon carrying the cam 128.

tion, between lines 0 and a includes the beginning of the constant rate of rise, part of which may be effective on the cam followers 126 to which valve actuators 116 are connected. The rise portion of the cam 28 or 128 is accordingly in excess of 180 so that as one cylinder overcomes compressibility and commences discharging fluid the other cylinder is finishing thereby assuring a constant pulseless flow.

The return strokes of the cam followers 126 and their connected valve actuators 116 is determined by follower control plates 121 and 122 which are separately adjustable by their threaded adjusting screws 123 carried in portions F2 of the frame F. The cam followers 126 are carried on follower blocks 127 with which the overload springs 126 are in engagement, the blocks 127 being urged towards each other by follower block springs 133 for engagement with the cam 128 or the cam follower control plates 121 or 122, dependent on the orientation of the cam 128 and the adjusted position of the cam follower control plates 121 and 122.

In FIGS. 2, 3 and 4 one unit comprising pump housing 141, pump cylinder 142, motor cylinder 135 and four way valve 115 is disposed above the other related unit with the upper pump cylinder 142 shown as to the right while the lower pump housing 141, and pump cylinder 142 is shown as to the left.

Flexible pipes 114a and 117a for supply and discharge of lower pressure fluid are shown.

The valve actuators 116 include valve actuator plates 154 connected thereto to position the spools of the valves 115 which in turn control the actuation of the motor pistons (not shown) in the motor cylinders 135.

The motor cylinders 135 are slidably supported at their outer ends on rods 155.on fixedly carried mounting portions of the frame F and at their opposite ends have driving yokes 156 extending to cross heads 157 mounted in the pump cylinders 142 for reciprocation. The cross heads 157 have the pistons 140 connected thereto for movement within the cylinder housings 141.

The pump cylinders 142 have pipes 143 extending through housings 141 to radial passageways 143a and circumferential passageways 143b around the pump pistons 140 for the delivery of the lubricating and sealing liquid previously referred to. Passageways 145b and 145a communicate with return pipe 145.

The pump cylinders 142 have cylinder heads 147 secured to housing 141 in which inlet and delivery valves are provided which can be of any suitable type. US. Pat. No. 3,245,429 to Bacino and Bowen, shows suitable valves.

For some designs, and in order to reduce stress concentration at very high pressures, the pump cylinder heads 147 are essentially flat plates with central portions concaved or convexed with straight bore holes 160 and 161 extending therefrom to sockets 162 in which the inlet and delivery valves are located and to which the supply and delivery connections are connected. The bore holes 160 and 161 are in nonintersecting relation to each other and are so disposed as not to be in the same plane.

Referring now to'FlG. 8, another form of servo action is there illustrated with which a feedback is obtained.

The cam 28, in Place of the follower 26, is provided with an idler pulley 226, urged by spring 225 into engagement with the cam 28 and which serves as a cam follower.

The idler pulley 226 has a cable 70 extending thereon to an adjustable end connection 71 to provide a zero adjustment. The cable 70 extends over an idler pulley 72 to a fixedly located four way motor piston control valve 215 urged in one direction by a spring 225a. The

' idler pulley 72 is carried by a movable pump piston 240 reciprocatory in a fixed pump cylinder 242. The ratio of movement of the idler pulley-follower 226 to the valve 215 is one to one which provides a smooth and accurate operation.

Referring now to FIG. 9, another form of servo action is illustrated with which a feed back is obtained.

The cam 28 has a cam follower 326 in engagement therewith. The follower 326 is carried on a lever which is normally held against movement by spring stops 76 which may serve as a fulcrum, or the barrels of the spring stops 76 may be attached to the rack 81. The lever 75 is pivotally connected to rack 81, guided by guide rollers 77 with which a pinion 78 is in engagement. A rack 79 in engagement with the pinion 78 is held by guide roller 80 and is connected to the cross head 357 to which the pump piston 340, movable in pump cylinder 342, is attached. The pinion 78 is mounted on and positions a movable valve 315 for motor cylinder positioning.

The mode of operation will now be pointed out.

The pumps 11 are operated by the motor 12, the motor 30 is operated to rotate the cam 28, 128, lubricating seal fluid is supplied by the sources 44, and fluid for pumping is available in the pipe 50.

The movement of the cam 28, 128, is effective to control the positioning of the valves 15, to supply pressure fluid for the lower pressure hydraulic circuit to actuate the cylinders 35, 135. It will be noted that in FIGS. 1B and 1C the load on the cam 28, 128 is small.

The cam 28, 128 has a constant rate of rise during the discharge or delivery stroke and upon the return stroke the cam follower control plates 121 and/or 122 become effective, dependent upon their setting, to arrest the return of the pistons. The pistons 36, 136 will remain at a constant position until the followers 26, 126 are again picked up by the advancing rate of rise portion of the cam 28, 128. The adjustment of the cam follower control plates 121 and 122 will determine the length of the stroke of the pump pistons 40, 140 so that when the proper adjustment is made the delivery of pumped liquid by one cylinder 142 will commence just as the delivery from the other cylinder 142 is being completed so that substantially pulseless liquid delivery will be effected.

The adjustment of the cam follower control plates permits adjustment of variable compressibilities of the same fluid at different pressure levels or the variable compressibility of different fluids at the same pressure level.

The use of a hydrocarbon oil, mineral oil or other fluent material having lubricating qualities and the characteristic of becoming substantially more viscous with pressure applied thereon, supplied from the source 44 through the pipes 43, 143 has been found effective to center the pump pistons 40, 140 and to seal the process fluid against leakage.

Such fluent materials are effective to provide a barrier seal because they heat up as they are subjected to shear when the pistons move. The small amount of heat changes the fluid flowing characteristics of the material and provide a thin film of fluid material for lubrication surrounded by non-moving viscous material which acts as a seal.

Not only is the function of lubrication served, but the use of packings which erode or are eroded is avoided at high pressures of the order of 45,000 psi and higher. Additionally, a straight bore cylinder 142 is achieved thereby reducing stresses to a minimum.

We claim:

1. Pumping apparatus comprising a fluid pump having a pair of cylinders each with a reciprocatory piston and inlet and delivery valves for supply of fluid to said cylinders for pumping by each of said pistons and delivery from said cylinders to a common discharge pipe, and means for actuating said pistons, said means comprising a rotary cam having on its exterior a constant rate of rise portion in excess of 180 for actuation of said pistons in overlapped relation to effect continuous pulseless flow from said cylinders and to said discharge pipe, and means for modifying the action of said cam to accommodate changes in compressibility of the fluid being pumped. 2. Pumping apparatus as defined in claim 1 in which an adjustable speed driving means is provided for rotating said cam. 3. Pumping apparatus as defined in claim 2 in which an overload clutch is interposed in said driving means. 4. Pumping apparatus as defined in claim 1 in which said means for modifying the action of said cam comprises at least one control member for adjustable positioning contiguous to said cam to modify the action of the rise portion of said cam.

5. Pumping apparatus as defined in claim 1 in which operating members are provided for said fluid delivery and discharge valves interposed between said valves and said cam, and said means for modifying the action of said cam comprises at least one slidably mounted control member for engagement with said operating members to modify the action of the return portion of said cam. 6. Pumping apparatus as defined in claim 1 in which said means for actuating said pistons comprises fluid pressure actuated means having reciprocatory members for actuating said reciprocatory pistons, and

control means for said fluid actuated means includmg pressure fluid supply means, and a fluid delivery and discharge valve to which said supply means is connected controlled by said rotary cam and said modifying means. 7. Pumping apparatus as defined in claim 6 in which said cam has a follower in engagement therewith, and

a feedback connection is provided between said piston and said follower. 8. Pumping apparatus as defined in claim 1 in which said fluid pressure actuated means includes fixedly mounted members and movable members connected to each of said pump pistons, and said movably mounted members and said fluid delivery and discharge valves are mounted for move ment together. 10. Pumping apparatus as defined in claim 6 in which said control means includes follower members engaged with said cam and to which said fluid delivery and discharge valves are connected, and resilient members for positioning said follower members. 11. Pumping apparatus as defined in claim 10 in which I said resilient members urge said follower members into engagement with said cam. l2. Pumping apparatus as defined in claim 10 in which resilient overload release members are provided in engagement with said follower members.-

13. Pumping apparatus comprising a fluid pump having a pair of cylinders each with a reciprocatory piston and inlet and delivery valves for supply of fluid to said cylinders for pumping by each of said pistons and delivery from said cylinders to a common discharge pipe, and

means including a single rotary cam having on its exterior a constant rate of rise portion in excess of for actuating said pistons in overlapped relation to effect constant pulseless flow from said cylinders at a predetermined compressibility of the fluid being pumped. 

1. Pumping apparatus comprising a fluid pump having a pair of cylinders each with a reciprocatory piston and inlet and delivery valves for supply of fluid to said cylinders for pumping by each of said pistons and delivery from said cylinders to a common discharge pipe, and means for actuating said pistons, said means comprising a rotary cam having on its exterior a constant rate of rise portion in excess of 180* for actuation of said pistons in overlapped relation to effect continuous pulseless flow from said cylinders and to said discharge pipe, and means for modifying the action of said cam to accommodate changes in compressibility of the fluid being pumped.
 2. Pumping apparatus as defined in claim 1 in which an adjustable speed driving means is provided for rotating said cam.
 3. Pumping apparatus as defined in claim 2 in which an overload clutch is interposed in said driving means.
 4. Pumping apparatus as defined in claim 1 in which said means for modifying the action of said cam comprises at least one control member for adjustable positioning contiguous to said cam to modify the action of the rise portion of said cam.
 5. Pumping apparatus as defined in claim 1 in which operating members are provided for said fluid delivery and discharge valves interposed between said valves and said cam, and said means for modifying the action of said cam comprises at least one slidably mounted control member for engagement with said operating members to modify the action of the return portion of said cam.
 6. Pumping apparatus as defined in claim 1 in which said means for actuating said pistons comprises fluid pressure actuated means having reciprocatory members for actuating said reciprocatory pistons, and control means for said fluid actuated means including pressure fluid supply means, and a fluid delivery and discharge valve to which said supply means is connected controlled by said rotary cam and said modIfying means.
 7. Pumping apparatus as defined in claim 6 in which said cam has a follower in engagement therewith, and a feedback connection is provided between said piston and said follower.
 8. Pumping apparatus as defined in claim 1 in which means is provided for preventing fluid leakage along said piston, said means including a fluid supply connection to said piston intermediate its ends, and means for supplying to said fluid supply connection a fluent material whose viscosity increases with pressure applied thereon.
 9. Pumping apparatus as defined in claim 6 in which said fluid pressure actuated means includes fixedly mounted members and movable members connected to each of said pump pistons, and said movably mounted members and said fluid delivery and discharge valves are mounted for movement together.
 10. Pumping apparatus as defined in claim 6 in which said control means includes follower members engaged with said cam and to which said fluid delivery and discharge valves are connected, and resilient members for positioning said follower members.
 11. Pumping apparatus as defined in claim 10 in which said resilient members urge said follower members into engagement with said cam.
 12. Pumping apparatus as defined in claim 10 in which resilient overload release members are provided in engagement with said follower members.
 13. Pumping apparatus comprising a fluid pump having a pair of cylinders each with a reciprocatory piston and inlet and delivery valves for supply of fluid to said cylinders for pumping by each of said pistons and delivery from said cylinders to a common discharge pipe, and means including a single rotary cam having on its exterior a constant rate of rise portion in excess of 180* for actuating said pistons in overlapped relation to effect constant pulseless flow from said cylinders at a predetermined compressibility of the fluid being pumped. 